Monday, December 17, 2018

On Polyuria

Q: All of the following are examples of "solute diuresis" except?

A) Glucosuria 
B) Resolution from azotemia 
C) Tissue catabolism 
D) Mannitol administration 
E) Nephrogenic diabetes insipidus

Answer: E

 Polyuria is defined as a urine output more than 3 Liter over 24 hours period in an adult patient. Polyuria is broadly classified into solute and water diuresis. Most of the diuresis is due to solute. Three major causes of water diuresis are
  •  Primary polydipsia
  • Central diabetes insipidus 
  • Nephrogenic diabetes insipidus 
The easiest way to differentiate between a solute or water diuresis is to look into urine osmolality. A solute diuresis usually has a urine osmolality of > 600 mosmol/kg and a water diuresis is usually has a urine osmolality < 600 mosmol/kg.



Adam D Jakes, Sunil Bhandari, Investigating polyuria, BMJ 2013;347:f6772

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